Selective adsorbent of benzene, toluene, ethylbenzene, and xylenes (BTEX) was developed based on mesoporous silica materials, RH-MCM-41. It was synthesized from rice husk silica and modified by silane reagents. The silane reagents used in this study were trimethylchlorosilane (TMS), triisopropylchlorosilane (TIPS), and phenyldimethylchlorosilane (PDMS). Physiochemical properties of synthesized materials were characterized by small-angle X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), and surface area analysis. Materials packed in passive air sampler were tested for BTEX uptake capacity. The tests were carried out under an influence of relative humidity (25 to 99 %). Overall, RH-MCM-41 modified by TMS outperformed compared to those modified by other silane agents. The comparative BTEX adsorption on this material and commercial graphitized carbon black was reported.

A Gram-positive bacterium, designated as strain B1(2015b), was isolated from the soil of the chemical factory “Organika-Azot” in Jaworzno, Poland. On the basis of 16S rRNA gene sequence analysis, the isolated strain was classified as a Bacillus thuringiensis species. Strain B1(2015b) is able to degrade ibuprofen and naproxen, however, these compounds are not sufficient carbon sources for this strain. In the presence of glucose, Bacillus thuringiensis B1(2015b) degrades ibuprofen and naproxen with higher efficiency. Twenty milligrams per liter of ibuprofen was degraded within 6 days and 6 mg l⁻¹ of naproxen was removed within 35 days. Simultaneously, the growth of the bacterial culture was observed. The obtained results suggest that Bacillus thuringiensis B1(2015b) appears to be a powerful and useful tool in the bioremediation of non-steroidal anti-inflammatory drugs-contaminated environment.

The competitive/simultaneous adsorption of arsenite (As(III)) and arsenate (As(V)) onto ferrihydrite is one of main processes controlling the distribution of arsenic under oxidizing conditions in the natural environment. Adsorption reactions of As(III) and As(V) with ferrihydrite were investigated by employing a combination of batch adsorption experiments and Fourier transform infrared (FTIR) spectroscopy measurements in single and binary systems, i.e., both As species were present at the same time. Isotherm studies showed that the adsorption of As(III) in the binary system was less than that in single system, indicating that As(V) hindered As(III) adsorption. The presence of As(III) had almost no impact on As(V) adsorption at pH 5 in the binary systems. Freundlich model described the equilibrium data well (R ² > 0.94), and the adsorption affinity onto ferrihydrite was in the following order: As(III)-single > As(III)-binary > As(V)-single > As(V)-binary. Kinetic data of As(III) and As(V) from single and binary systems were both well described by pseudo-second-order equation (R ² > 0.98). FTIR showed that after adsorbing of either As species, a new peak occurred at 826 cm⁻¹ due to the formation of Fe-O-As bonds, indicating that competition between As(III) and As(V) could take place on the surface sites as a result of the formation of a similar surface complexes.

In this study, we focused on the performance of phosphate recovery in the case of magnetic iron oxide (MIO) particles and iron oxide nanotubes (INTs) with synthetic wastewater. MIO particles were prepared by a co-precipitation method, and INTs were prepared with a potentiostatic anodization method of zerovalent iron foil in electrolyte-containing sulfate and fluoride. Although MIO had the fast adsorption rate, INT had a higher adsorption capacity per surface area rather than MIO. The adsorption isotherm of MIO and INT was approximated by a Freundlich type. Phosphate adsorbed on MIO and INT was effectively desorbed with alkaline solutions. For phosphate recovery, MIO needs a magnetic recovery device, whereas, when INT was used for phosphate recovery, another recovery step is not necessary. Both methods showed effective adsorption performance for phosphate recovery in wastewater.

The cell density-dependent gene expression in gram-negative bacteria is through the activity of acyl homoserine lactone signal molecules. The novel strain Pseudomonas putida JMQS1 isolated from detergent-contaminated soil exhibited quorum sensing along with its ability to degrade phenol. The response to Chromobacterium violaceum DSTS-1 mutant biosensor and luxI and luxR gene-specific amplification was used to characterize the quorum sensing property of the isolate. A regulation in the synthesis of various acyl homoserine lactone molecules, viz C₆HSL in the initial stages of phenol stress, C₈HSL during degradation, and 3OC₁₂HSL on completion of degradation could be identified by liquid chromatography-quadrupole time of flight. Thin-layer chromatography, Fourier transform infrared spectroscopy, and gas chromatography mass spectrometry confirmed the complete degradation of phenol in 48–56 h. P. putida JMQS1 exhibited adaptation over phenol stress through the selective activation of the quorum sensing signal molecules depending on the changing physiological conditions. This study proposes an efficient method for enhancing the degradation of toxic organic pollutants by the supplementation of acyl homoserine lactone signal molecules.

The effectiveness of gemini-modified palygorskite (PGS) as the novel remediation material in polycyclic aromatic hydrocarbons (PAHs)-contaminated water remediation was revealed and examined. The sorption behavior of gemini surfactants at the PGS/aqueous interface was addressed using a developed two-step adsorption and partition model (TAPM). The characterizations of gemini-modified PGS were investigated using infrared spectroscopy, cationic exchange capacity, and surface area analysis. The effects of pH, ionic strength, humic acid, and temperature on sorption of phenanthrene (PHE) to untreated and modified PGS were systematically studied. Analysis of the equilibrium data indicated that the sorption isotherms of gemini fitted TAPM well. The modification of PGS with gemini surfactants provided a favorable partition medium for PHE and enhanced PHE retention in solid particles. The solution parameters played significant effects on PHE sorption to the modified PGS. The sorption isotherms of PHE on PGS at different temperatures well fitted the Freundlich equation. Thermodynamic calculations confirmed that the sorption process of PHE on modified PGS was spontaneous and exothermic from 293 to 303 K. It is revealed that the modification with gemini surfactants probably offered some unique surface characteristics to the clay mineral as a new type of remediation material. This can provide a reference to the potential application of PGS in PAH-contaminated water remediation process.

In this study, the water quality of the Marreco River in the municipality of Toledo, PR, Brazil was investigated as part of a monitoring program. Conventional water pollution parameters (pH, turbidity, conductivity, COD, DO, ammonia, and total phosphorus) and metal elements were analyzed. Acute toxicity bioassays were conducted by the bacterial bioluminescence method, using the indicator Vibrio fischeri to evaluate the toxic effect of the contaminants. Principal components analysis (PCA) and Pearson’s correlation were applied to assess the statistical correlation between the physicochemical parameters and metals in the water samples. There is strong evidence, supported by Pearson and PCA analyses, of the presence of elevated levels of K and Ca associated with anthropogenic activities installed in the river basin.

The content and speciation of heavy metals can fundamentally affect the hydrolysis of sludge. This research study investigates the migration and transformation rule of heavy metals during the hydrolysis process by measuring the content of exchangeables (F1), bound to carbonates (F2), bound to Fe-Mn oxides (F3), bound to organic matter (F4), and residuals (F5) under different periods of time undergoing hydrolysis. The results show that the hydrolysis process generally stabilized Cu, Zn, Mn, Ni, Pb, Cr, and As by transforming the unstable states into structurally stable states. Such transformations and stabilization were primarily caused by the changes in local metal ion environment and bonding structure, oxidation of sulfides, pyrolyzation of organic matter, and evaporation of resulting volatile materials. An X-ray diffractometry (XRD) of the residuals conducted after hydrolysis indicated that hydrolysis did have a significant influence on the transportation and transformation of heavy metals.

Given that drugs and their degradation products are likely to occur as concoctions in wastewater, the degradation of a mixture of two nonsteroidal anti-inflammatory drugs (NSAIDs), diclofenac (DCF) and naproxen (NPX), was investigated by solar photolysis and titanium dioxide (TiO₂)-mediated solar photocatalysis using an immersion-well photoreactor. An equimolar ratio (1:1) of both NSAIDs in distilled water, drinking water, and river water was subjected to solar degradation. Solar photolysis of the DCF and NPX mixture was competitive particularly in drinking water and river water, as both drugs have the ability to undergo photolysis. However, the addition of TiO₂ in the mixture significantly enhanced the degradation rate of both APIs compared to solar photolysis alone. Mineralization, as measured by chemical oxygen demand (COD), was incomplete under all conditions investigated. TiO₂-mediated solar photocatalytic degradation of DCF and NPX mixtures produced 15 identifiable degradants corresponding to degradation of the individual NSAIDs, while two degradation products with much higher molecular weight than the parent NSAIDs were identified by liquid chromatography mass spectrometry (LC-MS) and Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS). This study showed that the solar light intensity and the water matrix appear to be the main factors influencing the overall performance of the solar photolysis and TiO₂-mediated solar photocatalysis for degradation of DCF and NPX mixtures.

Combining bioassays and analytical chemistry screenings is a powerful approach to assess emerging organic micropollutants which are the main contributors to toxic potentials in complex mixtures of water matrices. The aim of this study was to assess the cytotoxic effect of the occurrence of emerging organic micropollutants discharged into river water through industrial wastewater and treated effluents. The cytotoxic effects of surface water, treated effluents, and industrial wastewater were assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Then, organic micropollutants of various chemical groups were identified using a detailed non-target screening based on gas chromatography coupled with a mass spectrometry detector (GC/MS). A significant cytotoxic effect on human intestinal epithelial Caco-2 cells was observed for all the samples. Caco-2 cell viability decreased by 17.99, 33.77, and 24.54 % for surface water, treated wastewater, and industrial water, respectively. The organic chemical compounds responsible for this toxic potential were identified using non-target chemical screening. Statistical correlation between cytotoxicity and the presence of emerging contaminants revealed that the cytotoxic effect was mainly due (r ≥ 0.42) to the occurrence of cyclopentasiloxane, decamethyl and cyclohexasiloxane, dodecamethyl, D-limonene, and ergoline-8-methanol, 8,9-didehydro-6-methyl while cytotoxicity was highly negatively correlated (r ≤ −0.42) to 2-ethylhexyl salicylate, 3-isopropoxy-1,1,1,7,7,7-hexamethyl-3,5,5-tris(trimethyl siloxy)tetrasiloxane, 6-acetyl-1,1,2,4,4,7-hexamethyltetralin, and (3-aminopropyltriethoxysilane. Seventy-six other compounds detected by GC/MS showed no correlation to cytotoxicity.